According to the United States Environmental Protection Agency (EPA), air pollutants can cause numerous negative health impacts, such as nose and throat discomfort, headache, allergic airway and skin reactions, dizziness, trouble breathing, coughing, pain, and reduced lung function. According to the World Health Organization (WHO), air pollutants of major health concern include bacteria and viruses (e.g. influenza strain H1N1), cigarette smoke, radon, particulate matter, carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide. Outdoor and indoor air pollution often cause respiratory and other diseases, which can be fatal. In 2012, according to the World Health Organization, one in eight of total global deaths were the result of air pollution exposure. This finding more than doubles previous estimates and confirms that air pollution is now the world's largest single environmental health risk. The major causes of death due to air pollution are ischemic heart disease (40%), stroke (40%), chronic obstructive pulmonary disease (COPD) (11%), lung cancer (6%), and acute lower respiratory infections in children (3%). The air we inhale and exhale also contains chemicals that may not be harmful, but may be perceived to be unpleasant, such as pet odors or food smells. Health and performance relevant parameters include breathing rate, breathing volume, gas temperature and humidity, and the levels of gasses and chemicals, such as oxygen and carbon dioxide, in the exhaled air.
Air filtration devices can be used to mitigate the adverse health effects of airborne particulate matter, pathogens, allergens, and other pollutants. Some of these devices may be provided, for example, as masks that are worn over a person's mouth and/or nose. Most of these devices are passive filters that are designed to filter out a generic set of pollutants. These devices generally are not customized for each user's needs. Given their passive nature, these devices are also not configured to sense and adapt to changes in environmental conditions and/or a user's health conditions. In terms of aesthetics and ease of use, the bulk of these devices are typically unattractive and hinder the user's ability to communicate, as they are usually worn over a large part of the face.
In light of the above, there is a need for systems and methods that can accurately sense the surrounding environment and monitor users' health and health conditions, and that provide improved filtering performance for individual users. There is also a need for air filtration/respiratory devices that are effective, comfortable, easy to use by people suffering from various impairments, compact, aesthetically pleasing, can notify users of air pollution hazards and/or recommend certain corrective actions to users to improve their health and/or well-being, and that do not hinder a user's ability to communicate with others.